1. Field of the Invention
The present invention relates generally to an apparatus for maintaining an inkjet printer, and relates more specifically to technology for cleaning the nozzle surface of an inkjet head using a wiper.
2. Description of the Related Art
Inkjet printers print by discharging ink drops to a desired position from plural nozzles in a print head mounted on a bidirectionally travelling carriage.
Ink, dust, and other foreign matter adheres to the nozzle surface of the print head during printing, and the print head must therefore be cleaned at appropriate intervals while in a position outside of the printing area. One way to clean the nozzle surface is, for example, to provide a rubber wiper extending outside the nozzle surface of the print head and to move the print head across the wiper with the wiper deflected in contact with the nozzle surface so that the wiper wipes any ink and other foreign matter from the nozzle surface.
With this method, however, foreign matter removed from the nozzle surface of the print head by the wiper in this wiping process clings to the wiper. The next time the wiper with foreign matter adhering thereto wipes the nozzle surface, the foreign matter can enter the nozzles, thus clogging the nozzles or breaking the ink meniscus, resulting in dropped dots (i.e., non-printing dots).
Japanese Patent Laid-Open Publication (kokai) H8-39828 teaches an apparatus for resolving this problem by providing a blade member adjacent to the inkjet head so that when the inkjet head is moved, the blade member removes foreign matter adhering to the wiper so that the nozzle surface is cleaned with little foreign matter clinging to the wiper.
The problem with the apparatus taught in Kokai H8-39828 is that because the wiper position is constant (that is, contact between the wiper and any member contacting the wiper is constant) when the wiper wipes foreign matter from the nozzle surface and when foreign matter is removed from the wiper by the blade member, foreign matter removed from the wiper edge cannot be sufficiently removed. This means that foreign matter can still be transferred from the wiper to the nozzle surface when the wiper wipes the nozzle surface.
A further problem is that when the wiper returns from the deflected position to the normal non-deflected position when the wiper separates from the nozzle surface of the print head, foreign matter adhering to the wiper is flung from the wiper, thus soiling the inside of the printer and the print medium (such as paper). This is particularly a problem as printer size decreases.
The present invention is directed to a solution to this problem, and an object of the invention is to provide a maintenance apparatus able to wipe the nozzle surface of a print head with a wiper having no foreign matter adhering thereto.
A further object of the invention is to provide a maintenance apparatus able to prevent dispersion of foreign matter adhering to the wiper inside the device.
To achieve these objects, a maintenance apparatus according to the present invention has a drive mechanism for bidirectionally moving a print head having a nozzle surface in which are formed a plurality of nozzles; a wiper for wiping contamination from the nozzle surface; a remover connected for movement with the print head for wiping contamination from the wiper; a drive mechanism for moving the wiper in the direction of the plane of the nozzle surface from a standby position; and a control unit that controls the drive mechanisms so as to stop the wiper at a first position and to move the print head to a position where the print head is engaged by the wiper to remove contamination from the nozzle surface, and so as to stop the print head at a specific position and to move the wiper to a position where the wiper is engageable by the remover to remove contamination from the wiper.
By stopping the print head at a specific position and moving the wiper while the wiper is engaged with the remover so that the remover removes ink and foreign matter adhering to the wiper, foreign matter clinging to the wiper will not disperse in the direction of print head travel. Dirtying the inside of the unit is therefore reduced as compared with the prior art whereby the wiper is cleaned by moving the print head.
The control unit preferably controls the wiper drive mechanism to move the wiper to a second position farther beyond the plane of the nozzle surface than the first position to allow additional contamination to be removed from the wiper. This assures removal of foreign matter from a position farther from the cleaning edge of the wiper.
Yet further preferably, the print head is moved while the wiper is stopped at the second position to a position where the wiper and remover are engaged, and the wiper is then moved toward the standby position to remove the additional contamination from the wiper.
Yet further preferably, the remover is positioned on the maintenance area side of the print head, the maintenance area being adjacent to the printing area.
Yet further preferably, the remover is a flexible plate. One end of the remover is fixed to one side of the print head so that the remover forms a cantilever and the other free end forms a gap between the remover and the side of the print head. The wiper can be inserted to this gap between the print head and remover. By moving the wiper with the wiper while positioned between the print head and remover, ink and foreign matter adhering to the wiper can be removed.
A rake member for contact the wiper is preferably formed at the free end of the remover. When the wiper is then moved while in contact with the rake member, elastic force commensurate with deflection of the remover enables the rake member to wipe foreign matter from the wiper. In addition, the rake member meets the wiper after the wiper cleans and then separates from the nozzle surface, thereby preventing foreign matter on the wiper from scattering.
Yet further preferably, the rake member of the remover is at a position spaced apart by a certain distance from a plane defined by the nozzle surface in the direction opposite to the direction in which said wiper moves from its standby position to its first or second position. By thus slightly recessing the end (rake member) of the remover from the nozzle surface, the remover is prevented from contacting the printing paper when the print head moves through the printing area.
A wiper cleaner (second remover) for wiping contamination from the wiper is further preferably positioned on a side of the print head opposite to the side that the remover is positioned. This second remover removes a certain amount of foreign matter from the wiper through simple movement of the print head. The process for moving the wiper to clean the wiper with the first remover described above can thus be performed less frequently.